The death of Peter Lennon, Guardian journalist and documentary film-maker, causes a complicated kind of sadness. I met him first on joining the Guardian in 1999; he was at the paper on a freelance writing contract. Peter was funny, charming, and self-deprecating. He would occasionally participate in office discussions about how we should cover the Cannes film festival, without ever attempting to pull rank — as he was arguably entitled to do, given that he was a real live film-maker who had had something selected at Cannes.

Peter was the director of The Rocky Road to Dublin, a sensational movie anatomy of Ireland which was entered for the festival in the tumultuous year of 1968. The film grew out of a series of articles he had written based around interviews with priests, politicians, sportsmen and artists, and challenging what he saw as the Irish republic's reactionary complacency and dullness. It was shot by Jean-Luc Godard's cinematographer, Raoul Coutard, in an exhilarating hand-held style, and made Lennon, for a dizzying period, a brilliant fellow-traveller with the French New Wave.

Lennon was admired for his journalism, and for a sharp and witty collection of outsider-perspective essays about Paris in the 1960s entitled Foreign Correspondent. But it was as a film-maker – one who could have rivalled Frederick Wiseman or Albert and David Maysles – that he was really noticed. Why did he only make one film? What happened? His tale is part of the larger story of how being an independent film-maker is a back-breaking, heart-breaking business, and how building a career in the movies is subject to the awful tides of fate.

Lennon himself described how he experienced both good and bad luck as a film-maker. Elated by the response to his lid-lifting articles, and with a lightning bolt of inspiration, Lennon approached Coutard and asked him to be the cinematographer for his documentary movie version. Coutard shruggingly agreed with a "Ouais": he had recently fallen out, it transpired, with François Truffaut, who reportedly could not tolerate Coutard's bad temper, which was apparently caused by an attempt to quit smoking. The Frenchman resumed the habit during Lennon's shoot, so all was well, and Coutard made the film look glorious, giving it that ineffable zeitgeisty cool.

But it wasn't simply their expertise – Lennon's French crew had a cool detachment which Irish professionals might have lacked. With an Irish crew, every single daring aspect of the film might have triggered a furious personal row with someone, somewhere. With a shoestring movie, you rely on goodwill, people agreeing to be paid later, or not at all. And these were explosive issues.

The Irish establishment was frosty towards the film, but the movie's selection at Cannes (it was in the critics' week section) won them over – just a little. At Cannes itself, Peter's film was upstaged mightily when Godard and Truffaut stormed the stage just after its first screening and brought the festival to a halt. It was a curious omen.

And then? Well, nothing happened. Peter Lennon did not make another film. When The Rocky Road to Dublin was re-released six years ago, I wrote that he had been "cold-shouldered" by the Irish establishment, which was partly true. Irish cinemas wouldn't screen it, RTE didn't broadcast it, and it didn't actually get a full release until 2006.

But this, it seems, was not the whole story. Films need cash. Lennon's producer, Victor Hebert, though a generous and imaginative man, could not simply bankroll anything and everything, and Rocky Road, though a festival favourite, was no moneyspinner. Peter himself had a young family to support. He was enticed back to London by an offer to work for Harry Evans's Sunday Times. Journalism took up his time and energies. And here, again, is where the tides of luck and fate came in. Peter's film about Ireland was made in 1967, which was the right time for such a project. A few years later, "Ireland" meant the Troubles, the north, and the IRA. That was what producers and television companies wanted to hear about; Lennon did not find the subject congenial, and other subjects somehow did not suggest themselves.

Perhaps he did not have the monomaniacal career-ruthlessness you need. Hollywood calls it the "next job" mentality. While working on a movie, your every other thought is setting up the next movie – the next job. You have to keep an uninterrupted skein of engagements. If the thread breaks, you lose the momentum, and the phone goes quiet.

Well, it doesn't matter. Lennon, that superb writer and journalist, made a glorious film, The Rocky Road to Dublin, which was worth a dozen movies in the CV of a less distinguished man. It was such an energetic, punchy, daring film, not least in its challenge to the cronyist political establishment which infuriated the younger generation in Ireland – then as now. His film has something to say in Ireland in 2011, reeling from the Celtic Tiger comedown and badly let down by the same self-satisfied sort of politician whose back-slapping smugness was exposed in Rocky Road. It is available on DVD. Now is the time to watch Peter Lennon's masterpiece again.